Homogenized Feeding of Pulverized fuel with a controllable restriction in the pulverized fuel feed line

ABSTRACT

An apparatus for constantly supplying pulverized fuel at ambient or increased pressure includes a restrictable pulverized fuel control valve in the pulverized fuel feed line connecting the swirl layer of a dispensing vessel with a pulverized fuel collector is provided. This pulverized fuel control valve effects a compensation for and also attenuation of the pressure fluctuations, as occur in the pulverized fuel feed line, particularly during refill processes of the dispensing vessel. Special embodiments relate to a further homogenization by a fixed throttle facility and also auxiliary gas feeds into the pulverized fuel feed line.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority of German application No. 102011077911.6 DE filed Jun. 21, 2011. All of the applications are incorporated by reference herein in their entirety.

FIELD OF INVENTION

An apparatus for constantly supplying powdered fuel at ambient or increased pressure to a pulverized fuel collector with compensation for and also attenuation of pressure fluctuations in the pulverized fuel feed line is disclosed.

BACKGROUND OF INVENTION

Methods and apparatuses for the controlled supply of pneumatically delivered pulverized fuel to a consumer, in particular for the controlled supply of pulverized fuels into high-pressure gasification reactors are disclosed.

Pneumatically delivered pulverized fuel is understood to mean coal ground to a powder of various degrees of coalification, coke, if necessary thermally pretreated biomasses or crushable residual and waste materials from industry, trade and households. Other items able to be delivered include anorganic pulverized fuels, such as are used for instance for oxidizing crude iron and for desulfurization.

The pneumatic delivery of pulverized fuels is known in entrained-bed pressure gasification for the manufacture of energetic and synthetic gases or in the supply of pulverized fuel into furnace tuyeres. in such cases the pulverized fuel is supplied via a pressure sluice container to a dispensing container subjected to process pressure, from which the pulverized fuel is supplied to the consumer via one or more feed lines as a pulverized fuel/carrier gas suspension with a high loading density between 250-450 kg/m3. Consumers are understood to mean entrained-flow gasifiers, furnace tuyeres, boilers or apparatuses for oxidizing raw iron, wherein anorganic pulverized fuels are used.

Any low-oxygen gases for combustible pulverized fuel, in particular inert gases, like for instance nitrogen or carbon dioxide, which are free of condensable components, like for instance water vapor, can be used as compression gas for the pressure sluices and as carrier gases.

With these technologies, attempts are made to keep the flowing pulverized fuel quantity in the time unit constant to a large degree in order not to interfere with the loading process. The discontinuous filling of the dispensing container from the pressure sluices particularly generates pressure fluctuations, which disadvantageously influences the pressure difference used as a driving force for the delivery between the dispensing container and the collector. If the quantity of material to be fed changes, oscillations occur, which only decay and disappear after a long period of time. Patent DE 10 205 047 583 B4 therefore proposed to compensate for pressure fluctuations and dampen developing oscillations by means of the controlled supply of auxiliary gas in the immediate vicinity of the feed line inlet in the dispensing vessel or in the feed line. This technique has proven itself, but is nevertheless disadvantageous in that considerable quantities of auxiliary gas are supplied the carrier gas. This is likewise supplied to the consumer and puts a strain on the product to be generated. When using nitrogen as a carrier and auxiliary gas, the nitrogen content of the synthetic gas increases for instance during the pulverized fuel gasification process.

An object is to specify an apparatus for constant supply of the transported material to the consumer, with which differential pressure fluctuations between the dispensing container and consumer and thus quantity fluctuations are compensated for with a reduced quantity of auxiliary gas.

The problem is achieved by an apparatus having the features of the claims.

SUMMARY OF INVENTION

A proposed solution provides an apparatus for dispensing and supplying pulverized fuel under pressure to a consumer, for instance pulverized fuel to an entrained flow gasifier, wherein the pulverized transported material is supplied from an operational bunker which is under normal pressure, and is alternately supplied to a dispensing vessel via pressure sluices, in the lower part of which a tight swirl layer is produced by supplying swirl gas via a swirl bed, into which swirl layer one or more feed pipes immerse horizontally or vertically, through which the transported material is continuously fed to a pressurized collector/consumer 2, for instance a high pressure gasification reactor. In order to eliminate or attenuate pressure differences between the dispensing vessel and the consumer, a controllable and if necessary a fixed restriction is integrated into the pulverized fuel feed line. With the controllable restriction, e.g. in the form of a control valve, homogenization is achieved which in many cases renders unnecessary an additional auxiliary gas supply. As a result, it is possible to dispense with the auxiliary gas supply or to at least restrict the same. If auxiliary gas is supplied, it may be expedient to provide a fixed restriction in order to rule out an overlap in the control processes. The fixed restriction which is provided if necessary can be positioned in front of or behind an auxiliary gas supply arranged there. Auxiliary gas can also be supplied directly via the restriction of the feed line.

The pulverized fuel stream is measured in the feed pipe, wherein the determined measured value prespecifies the control variable for the quantity of swirl gas to be set by way of the control valve 3.3 and the position of the control valve 3.8 and if necessary for the quantity of auxiliary gas to be set if necessary by way of the control valve 3.3. It is furthermore advantageous to measure the flow speed of the pulverized fuel stream into the feed lines in the range between 2 to 8 m/s. Since the flow speed into the restrictions is increased several times, it is recommended that this be embodied in a wear-resistant manner.

Essential advantages of the disclosed claims compared with the prior art include it being possible to compensate for fluctuations in the pressure differences used as driving force for the pulverized fuel stream between the dispensing vessel and collector or pressure fluctuations in the collector by integrating a cross-sectionally changeable pulverized fuel control valve and if necessary a fixed restriction into the feed line(s) with or without auxiliary gas supply. At the same time, a constant pulverized fuel stream can be ensured, for instance during the refill processes, from the pressure sluice to the dispensing vessel. The feed lines leading out of the lower part of the dispensing container can be arranged horizontally or vertically. The pressure in the feed lines may lie between 0.1 and 6 MPa (1 and 60 bar). The feed line diameter may be selected as a function of the feed output and the number of feed pipes between 10 and 80 mm Cross-section-generating apparatuses without any essential change in the flow direction such as Venturi tubes, diaphragms and suchlike are suitable in particular as fixed throttle elements. With controllable throttle elements, cavities which result in pulverized fuel deposits are to be avoided.

If several pulverized fuel feed lines are fed from a dispensing vessel, the supply of swirl gas individual to the pulverized fuel feed line may potentially result in a mutual influencing of the pulverized fuel quantities into the pulverized fuel feed lines. The mutual influencing of the pulverized fuel quantities into the pulverized fuel feed lines is counteracted.

Advantageous developments are specified in the subclaims

The claimed features are described in 2 Figures and 2 examples, wherein an entrained flow gasification was selected as reference object.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the layout of the technology for high pressure pulverized fuel dispensing with a fixed restriction with and without auxiliary gas feed.

FIG. 2 shows the layout of the technology with a pulverized fuel control valve.

The same references refer to the same elements in the figures.

DETAILED DESCRIPTION OF INVENTION Example 1

An entrained flow gasification reactor 2 according to FIG. 1 is operated at a pressure of 4 MPa (40 bar) with an output of 500 MW. To this end, pulverized coal introduced at a grain size of <200 μm is supplied in a quantity of 90 Mg/h. The pulverized fuel is to this end supplied from an operational bunker to several pressure sluices (operational bunker and pressure sluices not shown) in order to place the pulverized coal under operational pressure by compressing the same with an inert gas.

The fill level of the dispensing vessel 1 is controlled by way of a fill level controller LIC 3.1. If the fill level in the dispensing vessel 1 is dropped to a minimum value, the refill process takes place from the pressure sluice. One or more pressure sluices can be arranged as a function of the quantity of pulverized fuel to be fed. The pulverized fuel feed lines 3.2 protrude vertically from the top into the lower part of the dispensing vessel 1, in which a very tight swirl layer with densities up to 450 kg/m3 is generated by way of a swirl bed by supplying swirl gas 3.3. By applying a pressure difference between the dispensing vessel 1 and the gasification reactor 2, the pulverized fuel carrier gas suspension generated in the swirl layer flows to the gasification reactor 2 via the feed lines 3.2. According to FIG. 1, three feed lines 3.2, each with a feed output of 30 Mg/h, are operated in this example, which open into the three burners 2.1 of the gasification reactor 2. In order to dampen differential pressure fluctuations between the dispensing vessel 1 and the gasification reactor and thus keep the feed output into the pulverized fuel feed lines 3.2 constant, a fixed throttle apparatus 3.6 is arranged in the feed line. Venturi tubes, diaphragms, tube assemblies and permanently integrated uncontrolled valves are considered as a fixed throttle facility 3. 6. Auxiliary gas can be introduced to the throttle facilities 3.2 immediately downstream of the feed tube inlet 3.7 or in front of, behind or immediately into the fixed throttle facility, as indicated for instance for the pulverized fuel feed line shown above. The quantity of pulverized fuel fed into the pulverized fuel lines 3.2 is measured in 3.5, wherein the measurement simultaneously prespecifies the control variables for the control valve 3.3 of the swirl gas quantity and if necessary for the control valve 3.4 for the auxiliary gas quantity into the auxiliary gas supply in 3.6 and 3.7

Example 2

An entrained flow gasifier 2 according to FIG. 2 is operated under the same conditions as in example 1. The restriction 3.8 is arranged here as a pulverized fuel control valve in direct vicinity of the gasification burner 2.1. The position of the pulverized fuel control valve 3.8 is influenced by the control signals from the flow measurement 3.5. There is also the possibility of supplying additional auxiliary gas via the auxiliary gas feed point 3.9 and/or at the feed tube inlet 3.7, also controlled by way of flow measurement 3.5, to the delivery tubes 3.2. Wear-resistant embodiments come into consideration as pulverized fuel control valves 3.8, the construction of which prevents the depositing of pulverized fuel and thus blockages.

In a particular embodiment, the pulverized fuel stream (3.5) is measured between the dispensing vessel 1 and the pulverized fuel control valve (3.8).

In a particular embodiment, the supplied auxiliary gas influences the pressure difference between the dispensing vessel 1 and the pulverized fuel collector 2 in addition to the pulverized fuel control valve and if necessary fixed throttle facility 3.6 and is used as a control variable for pulverized fuel transportation.

In a particular embodiment, the pulverized fuel control valve balances out pressure fluctuations in the pulverized fuel feed line 3.2 and ensures, with or without auxiliary gas, a constant pulverized coal flow in the pulverized fuel feed line 3.2.

In a particular embodiment, the pulverized fuel stream is fed to the burners 2.1 of a high pressure gasification facility 2 as pulverized fuel.

In a particular embodiment, the pulverized fuel stream is fed to the furnace tuyeres as pulverized coal.

In a particular embodiment, the pulverized fuel stream represents an anorganic material, which is supplied to a method for steel generation as regeneration means.

In a particular embodiment, the diameter of the feed lines 3.2 lies between 10 and 80 mm.

In a particular embodiment, the restrictable pulverized fuel control valve (3.8) can be controlled in accordance with a measurement of the pulverized fuel stream (3.5) arranged between the dispensing vessel 1 and the pulverized fuel control valve (3.8).

While specific embodiments have been described in detail, those with ordinary skill in the art will appreciate that various modifications and alternative to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of the appended claims, and any and all equivalents thereof. 

1. An apparatus for constant supply of pulverized fuel at ambient or increased pressure to a pulverized fuel collector with compensation for and also attenuation of pressure fluctuations in the pulverized fuel feed line, comprising: a dispensing vessel wherein a dense swirl layer is provided in the lower part of the dispensing vessel in the pulverized fuel filling by supplying a swirl gas via a control valve by way of a swirl bed; a pulverized fuel collector; a pulverized fuel feed line which reaches into the swirl layer with a first end and a second end is connected to the pulverized fuel collector; and a pulverized fuel control valve arranged in the pulverized fuel feed line, wherein a pressure difference driving the pulverized fuel is provided between the dispensing vessel and the pulverized fuel collector, wherein a measurement of a pulverized fuel stream is arranged in the pulverized fuel feed line, wherein the measurement of the pulverized fuel stream is actively connected with the control valve such that the quantity of supplied swirl gas takes place in accordance with the measured pulverized fuel stream, and wherein the measurement of the pulverized fuel stream is actively connected with the pulverized fuel control valve such that the passage cross-section is controlled in accordance with the measured pulverized fuel stream.
 2. The apparatus as claimed in claim 1, wherein the pulverized fuel feed line reaches horizontally into the swirl layer.
 3. The apparatus as claimed in claim 1, wherein the pulverized fuel feed line reaches vertically into the swirl layer.
 4. The apparatus as claimed in claim 1, wherein a fixed throttle facility is arranged in the pulverized fuel feed line between the dispensing vessel and the pulverized fuel control valve.
 5. The apparatus as claimed in claim 1, wherein an auxiliary gas supply is provided on a feed pipe inlet in the dispensing vessel.
 6. The apparatus as claimed in claim 1, wherein an auxiliary gas supply is provided in the pulverized fuel feed line between the dispensing vessel and measurement of the pulverized fuel stream.
 7. The apparatus as claimed in claim 4, wherein an auxiliary gas supply into the pulverized fuel feed line is provided between the dispensing vessel and the fixed throttle facility.
 8. The apparatus as claimed in claim 4, wherein an auxiliary gas supply is provided into the fixed throttle facility.
 9. The apparatus as claimed in claim 4, wherein an auxiliary gas supply into the pulverized fuel feed line is provided between the fixed throttle facility and the pulverized fuel collector.
 10. The apparatus as claimed in claim 1, wherein an auxiliary gas supply is provided into the pulverized fuel control valve.
 11. The apparatus as claimed in claim 5, wherein the measurement of the pulverized fuel stream is actively connected to the control valve for an auxiliary gas supply in order to meter the quantity of auxiliary gas.
 12. The apparatus as claimed in claim 1, wherein a plurality of pulverized fuel feed lines are arranged between the dispensing vessel and the pulverized fuel collector.
 13. The apparatus as claimed in claim 1, wherein the pulverized fuel is fed from an operational bunker to the dispensing vessel via at least one pressure sluice.
 14. The apparatus as claimed in claim 1, wherein the apparatus is provided by a pulverized coal feed system of a gasification facility operated above ambient pressure.
 15. The apparatus as claimed in claim 4, wherein the fixed throttle facility is provided by a Venturi tube.
 16. The apparatus as claimed in claim 4, wherein the fixed throttle facility is provided by a diaphragm.
 17. The apparatus as claimed in claim 4, wherein the fixed throttle facility is provided by a tubular assembly.
 18. The apparatus as claimed in claim 4, wherein the fixed throttle facility is provided by an uncontrolled valve.
 19. The apparatus as claimed in claim 1, wherein the pulverized fuel control valve is provided by a restrictable embodiment. 